Chronic ethanol exposure alters dopaminergic signal transduction processes

A number of data suggest that the chronic ethanol treatment induces derangements of cell membrane structure leading to modifications of membrane related processes. In particular, alterations have been observed in the mechanisms of neurotransmitter recognition and in the coupling of the receptor with the effector system. Phosphorylation of specific proteins by cyclic AMP stimulated protein kinases represent the final step in the biological response in several distinct functional processes. Ethanol neurotoxic action therefore may affect neurotransmitter availability and release as well as receptors effector systems and protein phosphorylation. In this line, chronic ethanol treatment in rats decreases cyclic AMP dependent protein kinase activity in rat striatal membrane fractions. When lysine rich histone type III was used as exogenous substrate, cyclic AMP stimulated 32P incorporation was still decreased in the ethanol group. These data favor the hypothesis of a decreased capability of the enzyme to phosphorylate in response to cAMP.